@techreport{oai:nifs-repository.repo.nii.ac.jp:00009620,
 author = {"Hino,  T. and Sagara,  A. and Nobuta,  Y. and Inoue,  N. and Hirohata,  Y. and Yamauchi,  Y. and Masuzaki,  S. and Noda,  N. and Suzuki,  H. and Komori,  A. and Ohyabu,  N. and Motojima,  O. and LHD, experimental group"},
 month = {Oct},
 note = {"Material probes have been installed at the inner walls along poloidal direction in LHD from the first experimental campaign. After each the campaign, the impurity deposition and the gas retention have been examined to clarify the plasma surface interaction and the degree of wall cleaning. In the 2nd campaign, the entire wall was considerably cleaned by helium glow discharge conditionings. For the 3rd and 4th campaigns, graphite tiles were installed at entire divertor strike region, and then the wall condition significantly changed compared to the case of stainless steel wall. The erosion of graphite took place during the main discharges and the eroded carbon deposited on the entire wall. In particular, the deposition thickness was large at the wall far from the plasma. Since the entire wall was well carbonized, amount of retained discharge gas such as H and He became large. In particular, the helium retention was large at the position close to the anodes used for helium glow discharge cleanings. One characteristics of the LHD wall is a large retention of helium gas since the wall temperature is limited below 368 K. In order to reduce the recycling of discharge gas, the wall heating before the experimental campaign and the surface heating between the main discharge shots are planned."},
 title = {Behavior of Plasma Facing Surface in the Large Helical Device},
 year = {2002}
}